Table saw with belt stop

ABSTRACT

A table saw in one embodiment includes a work-piece support surface, a shaping device support shaft automatically retractable along a retraction path to a location beneath the work-piece support surface in response to a sensed condition, a belt positioned across the retraction path, and a control system configured to cause the shaping device support shaft to retract along the retraction path in response to a sensed condition.

Cross-reference is made to U.S. Utility patent application Ser. No.12/547,818 entitled “Table Saw with Actuator Module” by Mehta et al.,which was filed on Aug. 26, 2009; U.S. Utility patent application Ser.No. 12/547,859 entitled “Table Saw with Dust Shield” by Chung, which wasfiled on Aug. 26, 2009; U.S. Utility patent application Ser. No.12/547,912 entitled “Table Saw with Positive Locking Mechanism” by Chunget al., which was filed on Aug. 26, 2009; U.S. Utility patentapplication Ser. No. 12/548,035 entitled “Table Saw with AlignmentPlate” by Chung et al., which was filed on Aug. 26, 2009; U.S. Utilitypatent application Ser. No. 12/548,156 entitled “Table Saw with SwingArm Support” by Chung et al., which was filed on Aug. 26, 2009; U.S.Utility patent application Ser. No. 12/548,201 entitled “Table Saw withMechanical Fuse” by Oberheim, which was filed on Aug. 26, 2009; U.S.Utility patent application Ser. No. 12/548,236 entitled “Table Saw withPressure Operated Actuator” by Fischer et al., which was filed on Aug.26, 2009; U.S. Utility patent application Ser. No. 12/548,263 entitled“Table Saw with Reset Mechanism” by Groth et al., which was filed onAug. 26, 2009; U.S. Utility patent application Ser. No. 12/548,280entitled “Table Saw with Linkage Drop System” by Holmes et al., whichwas filed on Aug. 26, 2009; U.S. Utility patent application Ser. No.12/548,317 entitled “Table Saw with Ratchet Mechanism” by Chung et al.,which was filed on Aug. 26, 2009; and U.S. Utility patent applicationSer. No. 12/548,342 entitled “Table Saw with Actuator Reset Mechanism”by Chung, which was filed on Aug. 26, 2009, the entirety of each ofwhich is incorporated herein by reference. The principles of the presentinvention may be combined with features disclosed in those patentapplications.

FIELD

The present disclosure relates to power tools and more particularly topower tools with exposed shaping devices.

BACKGROUND

A number of power tools have been produced to facilitate forming a workpiece into a desired shape. One such power tool is a table saw. A widerange of table saws are available for a variety of uses. Some table sawssuch as cabinet table saws are very heavy and relatively immobile. Othertable saws, sometimes referred to as jobsite table saws, are relativelylight. Jobsite table saws are thus portable so that a worker canposition the table saw at a job site. Some accuracy is typicallysacrificed in making a table saw sufficiently light to be mobile. Theconvenience of locating a table saw at a job site, however, makes jobsite table saws very desirable in applications such as generalconstruction projects.

All table saws, including cabinet table saws and job site table saws,present a safety concern because the saw blade of the table saw istypically very sharp and moving at a high rate of speed. Accordingly,severe injury such as severed digits and deep lacerations can occuralmost instantaneously. A number of different safety systems have beendeveloped for table saws in response to the dangers inherent in anexposed blade moving at high speed. One such safety system is a bladeguard. Blade guards movably enclose the saw blade, thereby providing aphysical barrier that must be moved before the rotating blade isexposed. While blade guards are effective to prevent some injuries, theblade guards can be removed by a user either for convenience of usingthe table saw or because the blade guard is not compatible for use witha particular shaping device. By way of example, a blade guard istypically not compatible with a dado blade and must typically be removedwhen performing non-through cuts.

Table saw safety systems have also been developed which are intended tostop the blade when a user's hand approaches or touches the blade.Various stopping devices have been developed including braking deviceswhich are physically inserted into the teeth of the blade. Suchapproaches are extremely effective. Upon actuation of this type ofbraking device, however, the blade is typically ruined because of thebraking member. Additionally, the braking member is typically destroyed.Accordingly, each time the safety device is actuated; significantresources must be expended to replace the blade and the braking member.Another shortcoming of this type of safety device is that the shapingdevice must be toothed. Moreover, if a spare blade and braking memberare not on hand, a user must travel to a store to obtain replacements.Thus, while effective, this type of safety system can be expensive andinconvenient.

Some safety systems incorporating blade braking systems also move theblade below the surface of the table saw once the blade has beenstopped. In this type of system, a latch is typically used to maintainthe blade in position above the table saw surface until the brakingsystem is activated. Once the blade has been moved to a location belowthe work piece support surface, movement of the blade must be stopped.

In view of the foregoing, it would be advantageous to provide a powertool with a safety system that does not damage the blade or othershaping device when stopping movement of the shaping device below thesurface of a work piece support surface. A further advantage would berealized by a stopping mechanism that fits within a small space. Astopping mechanism that could be reused would be further advantageous.

SUMMARY

In accordance with one embodiment, a table saw includes a work-piecesupport surface, a shaping device support shaft automaticallyretractable along a retraction path to a location beneath the work-piecesupport surface in response to a sensed condition, a belt positionedacross the retraction path, and a control system configured to cause theshaping device support shaft to retract along the retraction path inresponse to a sensed condition.

In another embodiment, a table saw includes a work piece supportsurface, a swing arm movable along a swing arm path from a first swingarm position whereat an arbor shaft rotatably supported by the swing armis positioned proximate to the work piece support surface and a secondswing arm position whereat the arbor shaft is distal to the work piecesupport surface, a stop belt positioned across the retraction path, anda control system configured to cause the swing arm to move along theswing arm path in response to a sensed condition.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate various embodiments of the presentdisclosure and together with a description serve to explain theprinciples of the disclosure.

FIG. 1 depicts a top perspective view of a table saw incorporating amitigation system in accordance with principles of the invention;

FIG. 2 depicts a bottom perspective view of the table saw of FIG. 1 withthe housing removed showing a movable carriage mounted on a pivotingframe beneath the work-piece support surface;

FIG. 3 depicts a perspective view of the swing arm assembly of the tablesaw of FIG. 1;

FIG. 4 depicts a partial perspective cross-sectional view of the swingarm assembly of FIG. 3 supported by a latch assembly including a latchhold that is biased against the swing arm assembly;

FIG. 4A depicts a schematic view of a controller operably connected tothe solenoid of FIG. 4;

FIG. 5 depicts a partial cross-sectional view of a swing arm assemblyheld in position by a latch pin biased against a latch hold;

FIG. 6 depicts a partial perspective view of the swing arm assembly andlatch assembly of FIG. 1 after the solenoid has been actuated therebyforcing the latch pin off of the latch hold such that the swing armassembly moves away from the latch assembly;

FIG. 7 depicts a partial perspective view of the swing arm assembly andlatch assembly of FIG. 1 after the swing arm assembly has cleared thelatch hold allowing the latch hold to be biased into the swing path;

FIG. 7A depicts the stop belt assembly of FIG. 2;

FIG. 8 depicts a partial perspective view of the swing arm assembly andlatch assembly of FIG. 1 as the swing arm assembly makes contact with astop belt assembly with the carriage initial position being in a lowposition;

FIG. 9 depicts a partial perspective view of the swing arm assembly andlatch assembly of FIG. 1 as the swing arm assembly makes contact with astop belt assembly with the carriage initial position being in a highposition;

FIG. 10 depicts a partial perspective cross-sectional view of a powertool with a latching pin that does not rotate with the swing armmechanism;

FIG. 11 depicts a partial perspective cross-sectional view of a powertool with a vertical swing arm and a positive locking mechanism;

FIG. 12 depicts a perspective view of the positive locking mechanism ofFIG. 11;

FIG. 13 depicts a partial cross-sectional view of the positive lockingmechanism of FIG. 11 as a solenoid pin contacts an actuation ramp in abore extending through the positive locking mechanism;

FIG. 14 depicts a partial cross-sectional view of the positive lockingmechanism of FIG. 11 as a strike plate is exposed to the solenoid pin ofFIG. 13 through the bore in the positive locking mechanism;

FIG. 15 depicts a partial cross-sectional view of the positive lockingmechanism of FIG. 11 as the solenoid pin of FIG. 13 impacts the strikeplate;

FIG. 16 depicts a partial cross-sectional view of the power tool of FIG.11 as the swing arm assembly contacts a release on a rebound latch;

FIG. 17 depicts a partial cross-sectional view of the power tool of FIG.11 with the swing arm assembly in contact with a latch foot on a reboundlatch for automatically positioning the rebound latch to arrestrebounding of the swing arm assembly off of a stop pad;

FIG. 18 depicts a partial cross-sectional view of the power tool of FIG.11 with the swing arm assembly arrested from rebounding by the reboundlatch;

FIG. 19 depicts a schematic representation of the relative positions ofa shaping tool as a horizontally mounted swing arm and a verticallymounted swing arm move a blade to a location beneath a work-piecesupport surface;

FIG. 20 depicts a perspective view of a positive locking mechanism whichautomatically aligns an actuating ramp with an actuator;

FIG. 21 depicts a cross-sectional view of a positive locking mechanismwith a roller that reduces wear of the mechanism and which can be usedto reduce movement of a latched swing arm assembly;

FIG. 22 depicts a cross-sectional view of a positive locking mechanismwhich can be used to reduce movement of a latched swing arm assembly;

FIGS. 23 and 24 depict a positive locking mechanism which engages a pinin a swing arm assembly and with an actuation ramp extending from thebody of the mechanism, and which rotates about an axis of rotation thatis not parallel to the axis along which a solenoid pin moves;

FIGS. 25 and 26 depict a positive locking mechanism which engages arecess in a swing arm assembly and with an actuation ramp defined in thebody of the mechanism, and which rotates about an axis of rotation thatis not parallel to the axis along which a solenoid pin moves;

FIGS. 27 and 28 depict a positive locking mechanism which engages arecess in a swing arm assembly and with an actuation ramp defined in thebody of the mechanism, and which rotates about an axis of rotation thatis parallel to the axis along which a solenoid pin moves;

FIGS. 29, 30, 31, and 32 depict alternative embodiments to the swing armassembly including a horizontal linear blade slide assembly, a diagonallinear blade slide assembly, and a vertical linear blade slide assembly;and

FIGS. 33, 34, 35, 36, and 37 depict a table top hood assembly andvarious components thereof for allowing a user unimpeded access to theinternal components of the table saw.

Corresponding reference characters indicate corresponding partsthroughout the several views. Like reference characters indicate likeparts throughout the several views.

DETAIL DESCRIPTION OF THE DISCLOSURE

While the power tools described herein are susceptible to variousmodifications and alternative forms, specific embodiments thereof havebeen shown by way of example in the drawings and will herein bedescribed in detail. It should be understood, however, that there is nointent to limit the power tools to the particular forms disclosed. Onthe contrary, the intention is to cover all combinations of features,modifications, equivalents, and alternatives falling within the spiritand scope of the invention as defined by the appended claims.

Referring to FIG. 1, a table saw 100 is shown. The table saw 100includes a base housing 102 and a work-piece support surface 104. Asplitter 106 is positioned adjacent to a blade 108 which extends fromwithin the base housing 102 to above the work-piece support surface 104.A blade guard (not shown) may be attached to the splitter 106. An angleindicator 110 indicates the angle of the blade 108 with respect to thework-piece support surface 104. A bevel adjust turn-wheel 112 may beused to establish the angle of the blade 108 with respect to thework-piece support surface 104 by pivoting a frame 114 (shown in FIG. 2)within the base housing 102.

A motor 116 which is powered through a switch 118 located on the basehousing 102, is supported by a carriage assembly 120. The carriageassembly 120 and a stop belt assembly 500 are supported by the frame114. The carriage assembly 120 includes a carriage 124 to which themotor 116 is mounted and two guiderails 126/128. The position of thecarriage 124 along the guiderails 126/128 is controlled by a bladeheight turn-wheel 130 through a gearing assembly 132 and a heightadjustment rod 134. The carriage 124 fixedly supports a latch assembly140 and pivotably supports a swing arm assembly 142.

The swing arm assembly 142, also shown in FIGS. 3 and 4, includes ahousing 144. A strike plate 146 and a rebound plate 148 are mounted onthe housing 144. The housing 144 encloses a power wheel 150 that isdriven by a power shaft 152. The power shaft 152 may be directly drivenby the motor 116 or by a reduction gear. A belt 154 transfers rotationalmovement from the power wheel 150 to a blade wheel 156 which rotates ona shaping device support shaft (also referred to as an “arbor shaft”)157. A nut 158 is used to affix the blade 108 (not shown in FIGS. 3 and4 for purpose of clarity) to the blade wheel 156. A tensioner 160maintains the belt 154 at a desired tension.

With additional reference to FIG. 5, the swing arm assembly 142 alsoincludes a lip 164 and a latch pin 166 which is biased by a spring 168toward a latch hold 170 which is part of the latch assembly 140. Inalternate embodiments, the latch pin is fixedly attached to the swingarm assembly 142. The latch hold 170 includes a latch ledge 172 (seeFIG. 5). As shown in FIG. 5, the latch ledge is formed complementarilyto the shape of the latch pin 166. The latch assembly 140 furtherincludes a base 180 and a solenoid 182 with a solenoid pin 184. Twosprings 186 and 188 are positioned between the base 180 and the latchhold 170 which is mounted by a pivot 190 to the carriage 124.

Operation of the table saw 100 is described with reference to FIGS. 1-5.Initially, the swing arm assembly 142 is maintained in a latchedposition with the latch pin 166 resting on the latch ledge 172 as shownin FIG. 5. In this position, the springs 188 and 186 are undercompression and exert a bias on the latch hold 170 about the pivot 190in a clockwise direction as viewed in FIG. 4. The latch hold 170 is thusbiased into contact with the lip 164 of the swing arm assembly 142 whichrestricts rotation of the latch hold 170.

Additionally, the blade wheel 156 is positioned sufficiently close tothe work-piece support surface 104 that the blade 108 extends above thework-piece support surface 104 as shown in FIG. 1. A user operates thebevel adjust turn wheel 112 to pivot the frame 114 with respect to thework-piece support surface 104 to establish a desired angle between theblade 108 and the work-piece support surface 104. The user furtheroperates the blade height adjustment turn-wheel 130 to move the carriage124 along the guiderails 126/128 to establish a desired height of theblade 108 above the work-piece support surface 104.

Using the switch 118, power is then applied to the motor 116 causing theoutput shaft 152 and the power wheel 150 to rotate. Rotation of thepower wheel 150 causes the belt 154 to rotate the blade wheel 156 andthe blade 108 which is mounted on the blade wheel 156. A work-piece maythen be shaped by moving the work-piece into contact with the blade 108.

The table saw 100 includes a sensing and control circuit 159 (not shown)which activates the solenoid 182 in response to a sensed condition. Anydesired sensing and control circuit may be used for this purpose. Oneacceptable sensing and control circuit is described in U.S. Pat. No.6,922,153, the entire contents of which are herein incorporated byreference. The safety detection and protection system described in the'153 patent senses an unsafe condition and provides a control signalwhich, in the table saw 100, is used to actuate the solenoid 182.

Upon actuation of the solenoid 182, the solenoid pin 184 is forcedoutwardly from the solenoid 182. When the swing arm assembly 142 ismaintained in a latched position with the latch pin 166 resting on thelatch ledge 172 as shown in FIG. 5, the strike plate 146 is aligned withthe solenoid pin 184. Accordingly, as the solenoid pin 184 is forced outof the solenoid 182, the solenoid pin 184 impacts the strike plate 146.

The shapes of the latch pin 166 and the latch ledge 172 are selectedsuch that the impact of the solenoid pin 184 on the strike plate 146generates a force tending to push the latch pin 166 against the spring168. The spring constant of the spring 168 and the operatingcharacteristics of the solenoid 182 are selected such that when thesolenoid pin 184 impacts the strike plate 146 the generated force issufficient to compress the spring 168 and to force the latch pin 166into a position whereat the swing arm assembly 142 is no longermaintained in position adjacent to the latch assembly 140 by the latchpin 166. In embodiments with a spring 168 biasing the latch pin 166, thesprings 188 and 186 may be omitted. In embodiments with a rigid latchpin 166, the generated force causes the latch hold 170 to rotate aboutthe pivot 190 in a counterclockwise direction thereby forcing thesprings 186 and 188 into further compression. When the latch hold 170has rotated sufficiently, the latch ledge 172 moves out from underneaththe latch pin 166.

In either event, the swing arm assembly 142 is no longer supported bythe latch hold 170. Consequently, the swing arm assembly 142 pivotsabout the power shaft 152 in the direction of the arrow 200 of FIG. 6such that the blade wheel 156 moves away from the work-piece supportsurface 104 through the position shown in FIG. 6 to the position shownin FIG. 7. Accordingly, the blade 108 is pulled by the swing armassembly 142 in a direction away from the work-piece support surface104.

Because the latch ledge 172 is formed complementarily to the shape ofthe latch pin 166, the wear of the latch ledge 172 and the latch pin 166during the de-latching described above is reduced. Accordingly, thepressure needed to effect de-latching does not change significantly overmultiple actuations of the solenoid 182. As the swing arm assembly 142moves in the direction of the arrow 200, the rebound plate 148 of theswing arm assembly 142 rotates below the bottom surface of the latchhold 170. At this point, rotation of the latch hold 170 about the pivot190 is no longer restrained by the swing arm assembly 142.

The configuration of FIG. 7 further shows the swing arm assembly 142rotated to a position whereat the swing arm assembly 142 contacts thestop belt assembly 500. The stop belt assembly 500, shown in FIG. 7A,includes a belt 502, a first anchor portion 504, a second anchor portion506, a plurality of mounting holes 508, and a plurality of mountingscrews 510. The first anchor portion 504 is mounted to the latch holdbase 180. The second anchor portion 506 is mounted to the frame 114. Inone embodiment the belt 502 is made from a stretchable material, e.g.,NYLON. NYLON further provides friction as the swing arm assembly 142contacts the stop belt 502. As depicted in FIG. 2, the first anchorportion 504 is closer to the work-piece support surface 104.

In operation, the swing arm assembly 142 moves clockwise after actuationand makes contact with the belt 502. The belt 502 deforms and takes upthe kinetic energy of the swing arm assembly 142. Accordingly, furtherrotation of the swing arm assembly 142 in the direction of the arrow 200of FIG. 6 is impeded by the stop belt assembly 500. At this position,the blade 108 is completely located below the work-piece support surface104. Due to the characteristic of the belt 502, kinetic energy from theswing arm assembly 142 is dissipated such that at the end of theclockwise travel the swing arm assembly 142 does not reboundsignificantly. Thus, the material, length and the design of the belt 502is such that the swing arm assembly 142 stops rotation and does notrebound above the work-piece surface 104. Therefore, an operator abovethe work-piece support surface 104 cannot be injured by the blade 108.In some embodiments, rebound of the swing arm assembly 142 may occur. Insuch embodiments, the latch hold 170 may be configured with reboundledges and the swing arm assembly 142 may be configured with a reboundplate such as those described in U.S. Utility patent application Ser.No. 12/547,818 entitled “Table Saw with Actuator Module” by Mehta etal., which was filed on Aug. 26, 2009.

The position of the stop belt assembly 500 is selected in the embodimentof FIG. 2 to ensure that the swing arm assembly 142 contacts the stopbelt assembly 500 at the foot 192 of the swing arm assembly 142regardless of the initial height of the carriage 124. Referring to FIGS.8 and 9, the carriage 124 is depicted at different initial heights. Forexample, the carriage 124 in FIG. 8 has a lower initial position thanthe carriage 124 depicted in FIG. 9. Nonetheless, the foot 192 receivesthe force of the impact when the swing arm assembly 142 contacts thestop belt assembly 500 regardless of the initial height of the carriage124. Accordingly, while the materials used to form the foot 192, and thestrike plate 146 are selected to absorb multiple impacts, lightermaterials may be used in other areas of the swing arm assembly 142 tominimize weight of the table saw 100.

Once the sensed condition has been cleared, the swing arm assembly 142is reset by moving the latch hold 170 out of the swing path. This iseffected by compressing the springs 188 and 186. The swing arm assembly142 may then be rotated in a counterclockwise direction about the outputshaft 152 until the rebound plate 148 is adjacent to the upper surfaceof the latch hold 170. The latch hold 170 is then released and thesprings 188 and 186 bias the latch hold 170 about the pivot 190 intocontact with the lip 164 of the swing arm assembly 142 which restrictsrotation of the latch hold 170. Additionally, the swing arm assembly 142is maintained in a latched position with the latch pin 166 resting onthe latch ledge 172 as shown in FIG. 5.

The table saw 100 thus actively monitors for an unsafe condition andinitiates mitigation action automatically in the event an unsafecondition is sensed. Additionally, movement and subsequent stopping ofthe swing arm assembly 142 is accomplished without requiring physicalcontact with the blade 108. Accordingly, the blade 108 is not damaged bythe mitigation action.

Moreover, because the mitigation action does not require interactionwith the blade 108, the mitigation system of the table saw 100 may beused with other shaping devices such as sanding wheels, blades withvarying dado blades, and molding head cutters, without requiring anymodification to the mitigation system. Additionally, because the movingcomponents of the mitigation system can be mounted on the frame 114, themitigation system can be used with any desired blade height or bevelangle.

The mitigation system discussed with respect to the table saw 100 can beimplemented using very light materials, and is thus amenable toincorporation into a variety of power tools including bench top saws andportable saws. For example, the components which are subjected toincreased stress within the mitigation system, such as the solenoid pin184, the latch hold 170, the rebound plate 148, and the strike plate146, can be made of more durable materials including metals to withstandthe impacts and stresses of activating the mitigation system. Othercomponents, including the housings, may be fabricated from morelightweight materials to minimize the weight of the power tool.

If desired, the components of the table saw 100 may repositioned withinthe housing 102. By way of example, FIG. 10 depicts a power tool 202with a latch pin 204 positioned within a base 206. The latch pin 204 isbiased by a spring (not shown) toward a latch hold 208 which ispivotably mounted by a pivot 210 to a swing arm assembly 212. In thisembodiment, the latch hold 208 includes a latch ledge 214 and a singlerebound ledge 216. The base 206 includes a rebound plate 218. Anadditional rebound plate 220 is provided on the base 206 as a safetymeasure in the event the latch hold 208 does not move with the designedspeed in a manner similar to the latch hold 170. Operation of the powertool 202 as configured in the manner of FIG. 10 is substantiallyidentical to operation of the table saw 100 as configured in FIG. 4.

A further example of rearranged components is shown in FIG. 11, whereina power tool 230 includes a swing arm assembly 232 mounted vertically ona carriage assembly 234 below a slot 236 in a work support surface 238.The power tool 230 further includes a solenoid 240 and a rebound latch242, both of which are also mounted to the carriage assembly 234. Theswing arm assembly 232 includes a power wheel 244 which rotates a bladewheel 246 through a belt 248. The swing arm assembly 232 furtherincludes a strike plate 250 and a latch plate 252.

The swing arm assembly 232 is maintained in the position shown in FIG.11 by a latch pin 254. The latch pin 254 is biased by a spring 256 intoa latch recess 258 in the swing arm assembly 232. The pin 254, alsoshown in FIG. 12, includes a head 260 and a body 262. A bore 264 extendsthrough the body 262 and includes an actuation ramp 266. The surface ofthe actuation ramp 266 is angled from an upper portion 268 of the bore264 to a lower portion 270 of the bore 264.

The rebound latch 242 is pivotably mounted to the carriage assembly 234by a pivot 272. A spring 274 biases the rebound latch 242 in a counterclockwise direction as viewed in FIG. 11. The rebound latch 242 includesa rebound ledge 276, a release 278, and a latch foot 280. A stop pad 282is also mounted to the carriage assembly 234.

Operation of the power tool 230 may be substantially identical tooperation of the table saw 100 through the firing of the solenoid 240.When the solenoid 240 is actuated, however, a solenoid pin 290, shown inFIG. 13, is forced outwardly from the solenoid 240 into contact with theactuation ramp 266. The shape of the solenoid pin 290 and the actuationramp 266 forces the latch pin 254 against the spring 256. The forcetransferred from the solenoid 240 is sufficient to overcome the bias ofthe spring 256. Accordingly, the spring 256 is compressed and the pin254 moves outwardly from the latch recess 258 to the position shown inFIG. 14.

In FIG. 14, the latch pin 254 has moved to a position whereat the strikeplate 250 of the swing arm assembly 232 is exposed to the solenoid pin290 through the lower portion 270 of the bore 264. Additionally, thehead 260 of the latch pin 254 has been moved to a position whereatrotation of the swing arm assembly 232 is not inhibited by the latch pin254, even though a portion of the latch pin 254 may remain within therecess 258.

Continued movement of the solenoid pin 290 outwardly from the solenoid240 causes the solenoid pin 290 to contact the strike plate 250 asdepicted in FIG. 15. The solenoid pin 290 transfers sufficient force tothe strike plate 250 to cause the swing arm assembly 232 to rotate aboutthe power wheel 244 in a manner similar to the rotation of the swing armassembly 142 described above. Rotation of the swing arm assembly 232brings the swing arm assembly 232 into contact with the release 278 ofthe rebound latch 242 as shown in FIG. 16. The force of the swing armassembly 232 is sufficient to overcome the bias of the spring 274thereby rotating the rebound latch 242 about the pivot 272 in thedirection of the arrow 284.

Once the rebound latch 242 has rotated sufficiently, the swing armassembly 232 slides past the release 278 and into contact with the latchfoot 280 as shown in FIG. 17. Continued rotation of the swing armassembly 232 forces the latch foot 280 downward, causing the reboundlatch 242 to rotate in the direction of the arrow 286 of FIG. 17. As therebound latch 242 rotates in the direction of the arrow 286, the reboundledge 276 is rotated into a position above the latch plate 252 as shownin FIG. 18.

The swing arm assembly 232 then rotates into contact with the stop pad282. In the event the swing arm assembly 232 begins to rebound off ofthe stop pad 282, the latch plate 252 moves into contact with therebound ledge 276 and rotation of the swing arm assembly 232 isarrested.

The vertical arm configuration of the tool 230 may be desirable inapplications wherein injury is most likely to occur as a result ofmovement parallel to the surface of the work piece support surface. Byway of example, FIG. 19 is a schematic of a work piece support surface300 with a shaping device 302, for example, a blade 302, extending abovethe surface of the work piece support surface 300. The shaping device302 rotates about an axis defined by a blade wheel 304. In a horizontalswing arm configuration, the blade wheel 304 is driven by a power shaft306. In a vertical swing arm configuration, the blade wheel 304 isdriven by a power shaft 308.

A work piece, for purpose of this example, is moved by a user toward theblade 302 in the direction of the arrow 310. Thus, the point at whichthe user is most likely to come into accidental contact with the shapingdevice 302 is at or near the location 312. When accelerated such as by asolenoid 182, the blade wheel 304, in a horizontal swing armconfiguration, rotates from the position indicated by the blade wheel304 to the position indicated by the blade wheel 304 _(H1) in a firsttime interval. The location of the shaping device 302 associated withthe blade wheel 304 _(H1) is blade 302 _(H1). Thus, the blade 302 hasmoved from the location 312 to the location 314.

During the same time interval, the blade wheel 304, in a vertical swingarm configuration, rotates from the position indicated by the bladewheel 304 to the position indicated by the blade wheel 304 _(V1). Thelocation of the shaping device 302 associated with the blade wheel 304_(V1) is blade 302 _(V1). Thus, the blade 302 has moved from thelocation 312 to the location 316. Accordingly, the blade 302 is movedfarther away from the contact point 312 by the vertical configurationthan by the horizontal configuration.

Likewise, the blade wheel 304, in a horizontal swing arm configuration,rotates from the position indicated by the blade wheel 304 _(H1) to theposition indicated by the blade wheel 304 _(H2) in a second timeinterval. The location of the shaping device 302 associated with theblade wheel 304 _(H2) is blade 302 _(H2). Thus, the blade 302 has movedfrom the location 312 to the location 316 over two time intervals.

During the second time interval, the blade wheel 304, in a verticalswing arm configuration, rotates from the position indicated by theblade wheel 304 _(V1) to the position indicated by the blade wheel 304_(V2). The location of the shaping device 302 associated with the bladewheel 304 _(V2) is blade 302 _(V2). Thus, the blade 302 has moved fromthe location 312 to the location 318. Accordingly, the blade 302 movesaway from the contact point 312 by about a factor of two in the verticalconfiguration as compared to the horizontal configuration.

Thus, in applications wherein an injury is most likely to occur at oneside of the shaping device, a vertically oriented swing arm may be usedto mitigate injury. Most table saw applications will fit into thisscenario if a blade guard is installed. FIG. 19 similarly illustratesthat the horizontal swing arm configuration moves the blade downwardlyat a faster rate. Thus, in applications wherein the injury is mostlikely to occur at the top of the shaping device, a horizontal swing armconfiguration may be used to mitigate injury.

As described above, operation of the latch pin 254 is significantlydifferent from operation of the latch pin 166. Specifically, the latchpin 166 is operated by applying a force to the swing arm assembly 142.In contrast, the latch pin 254 is relatively immune to activation byapplication of force to the swing arm assembly 232. Accordingly, thelatch pin 254 is a positive locking mechanism that is not susceptible tounintentional unlocking absent complete failure of the latch pin 254.The latch pin 254 may thus be used in swing arms that are positioned inany desired orientation.

A variety of positive locking mechanisms, i.e., mechanisms wherein alatch is moved prior to application of rotational force to the swing armassembly, may be incorporated into power tools. One example of anotherpositive locking mechanism is the latch pin 320 of FIG. 20. The latchpin 320 includes a head 322 and a body 324. The latch pin 320 furtherincludes an actuation ramp 326 within a bore 328. While the latch pin320 is similar to the latch pin 254, the body 324 of the latch pin 320is substantially wider than the cylindrical body 262 of the latch pin254. Thus, the bore 328 of the latch pin 320 is easily maintained inalignment with a solenoid pin. Additionally, a non-cylindrical body suchas the body 324 may provide enhanced alignment of the swing arm withwhich the body 324 is used.

Another positive locking mechanism is the latch pin 330 of FIG. 21. Thelatch pin 330 includes a head 332 and a body 334. The body 334 may beany desired shape including rectangular or cylindrical. The latch pin330 further includes an actuation ramp 336 within a bore 338. The latchpin 330 also includes a wheel 340 rotatably mounted in the head 332. Thewheel 340 reduces wear on the latch pin 330. Additionally, the wheel 340in this embodiment is configured to contact only one side of a recess342 in a swing arm 344. Accordingly, by providing another member whichlimits the upward or counter-clockwise travel of the swing arm 344, thewheel 340 is used to “pinch” the swing arm 344 to reduce or eliminateundesired movement of the swing arm 344.

Another positive locking mechanism is the latch pin 360 of FIG. 22. Thelatch pin 360 includes a head 362 and a body 364. The body 364 may beany desired shape including rectangular or cylindrical. The latch pin360 further includes an actuation ramp 366 within a bore 368. The head362 in this embodiment is configured to contact opposing tapered sidesof a recess 372 in a swing arm 384. Accordingly, seating of the head 362in the recess 372 eliminates undesired movement of the swing arm 384.Further reduction in non-axial movement of the latch pin 360 whilepermitting axial movement for locking and unlocking the swing arm 384 isprovided by oil impregnated bushings 374.

A positive locking mechanism may also be provided in the form of arotating latch pin such as the latch pin 380 depicted in FIGS. 23 and24. The latch pin 380 includes a head 382 and a body 384. The latch pin380 further includes an actuation ramp 386 extending from the body 384.The head 382 includes a hook portion 388 which engages a retaining pin390 in a swing arm 392. The latch pin 380 is pivotably supported by apivot pin 394 and biased toward the retaining pin 390 by a spring 396.When the hook portion 388 engages the retaining pin 390, the actuationramp 386 is aligned with a solenoid pin 398.

In operation, movement of the solenoid pin 398 causes the solenoid pin398 to impinge the actuation ramp 386 of the latch pin 380 imparting arotational force to the latch pin 380. The actuation ramp 386 thusconverts axial force from the solenoid pin 398 to a rotational force.The rotational force overcomes the bias of the spring 396 causing thelatch pin 380 to rotate in a counterclockwise direction about the pivotpin 394. The shape of the hook portion 388 and the retaining pin 390along with the location of the hook portion 388 relative to the pivotpin 394 is selected to ensure that an upward force is not imparted ontothe retaining pin 390 from the latch pin 380 during this rotation. Oncethe actuation ramp 386 has rotated sufficiently, the solenoid pin 398continues to move axially into contact with the swing arm 392.

The latch pin 400 depicted in FIGS. 25 and 26 is another positivelocking mechanism in the form of rotating latch pin. The latch pin 400includes a head 402 and a body 404. The latch pin 400 further includesan actuation ramp 406 extending from the body 404. The head 402 includesa lip portion 408 which engages a retaining recess 410 in a swing arm412. The latch pin 400 is pivotably supported by a pivot pin 414 andbiased toward the retaining recess 410 by a spring 416. When the lipportion 408 engages the retaining recess 410, the actuation ramp 416 isaligned with a solenoid pin 418.

In operation, movement of the solenoid pin 418 causes the solenoid pin418 to impinge the actuation ramp 406 of the latch pin 400 imparting arotational force to the latch pin 400. The rotational force overcomesthe bias of the spring 416 causing the latch pin 400 to rotate in aclockwise direction about the pivot pin 414. The shape of the lipportion 408 and the retaining recess 410 along with the location of thelip portion 408 relative to the pivot pin 414 is selected to ensure thatan upward force is not imparted onto the retaining recess 410 from thelatch pin 404 during this rotation. Once the actuation ramp 406 hasrotated sufficiently, the solenoid pin 418 continues to move axiallyinto contact with the swing arm 412.

The solenoid pin 418 in this embodiment impinges a strike plate portion420 which is pivotably attached to a lower swing arm housing 422 by apivot pin 424. Spring washers 426 positioned between the strike plateportion 420 and the lower swing arm housing 422 bias the strike plateportion 420 into a position aligned with the solenoid pin 418 when thelip portion 408 is within the retaining recess 410. When the solenoidpin 418 impacts the strike plate portion 420, the spring washers 426 arecompressed thereby reducing the peak force that is transferred from thestrike plate portion 420 to the other components of the swing arm 412.This allows lighter materials to be used for some components of theswing arm 412 while ensuring a rapid acceleration of the swing arm 412.

The latch pin 430 depicted in FIGS. 27 and 28 is another positivelocking mechanism in the form of rotating latch pin. The latch pin 430includes a head 432 and a body 434. The latch pin 430 further includesan actuation ramp 436 extending into the body 434. The head 432 includesa lip portion 438 which engages a retaining recess 440 in a swing arm442. The latch pin 430 is pivotably supported by a pivot pin 444 andbiased toward the retaining recess 440 by a radial spring 446. When thelip portion 438 engages the retaining recess 440, the actuation ramp 436is aligned with a solenoid pin (not shown). If desired, a second latchpin (not shown), substantially identical to the latch pin 430, may beprovided in opposition to the latch pin 430.

In operation, movement of the solenoid pin (not shown) causes thesolenoid pin (not shown) to impinge the actuation ramp 436 of the latchpin 430 and the axial force is translated into a rotational force by theactuating ramp 436 imparting a rotational force to the latch pin 430.The rotational force overcomes the bias of the spring 446 causing thelatch pin 430 to rotate in a clockwise direction about the pivot pin 444and outwardly from the swing arm 442. Once the actuation ramp 436 hasrotated sufficiently, the solenoid pin (not shown) continues to moveaxially into contact with a strike plate 448 on the swing arm 442.

With reference to FIG. 29, a horizontal linear blade slide assembly 550includes an actuator 552, a release hook 554, a sliding blade assembly560, a carriage 562, height adjustment guide rails 564/566, a heightadjust bar 568, a height adjust worm gear set 570, an end bar 574, stopcatch pads 576, catch mechanisms 578, an arbor shaft 580, a blade 582,work-piece support surface 584, and slide blade assembly guide rails586/588. In one embodiment, shown in FIG. 30, the catch mechanism 578includes bonnet latches 590 while the stop catch pads 576 include bonnetcatches 592.

In operation, the sliding blade assembly 560 is configured to movehorizontally in the direction of an arrow denoted by the referencenumeral 572 in order to move the blade away from a horizontally movingobject that is not to be harmed by the blade 582. In response to asensed event, the actuator 552 releases the release hook 554 anddisplaces the sliding blade assembly 560 in the direction of the arrow572. The sliding blade assembly 560 glides on slide blade assembly guiderails 586/588 until the catch mechanisms 578 come in contact with thestop catch pads 576 which are supported by the end bar 574. The stopcatch pads 576 and the catch mechanisms 578 prevent the sliding bladeassembly 560 from rebounding off of the stop catch pads 576 to ensurethe blade 580 does not return to a position that could harm the object.In one embodiment, the bonnet latches 590 engage bonnet catches 592 toprevent rebounding of the sliding blade assembly 560. The horizontalmovement of the sliding blade assembly 560 does not interfere with theheight adjustment mechanism including the height adjust bar 568, theheight adjust worm gear set 570, and the height adjustment guide rails564/566.

In an alternative embodiment, a diagonal linear blade slide assembly 600is depicted in FIG. 31. The diagonal linear blade slide assembly 600includes similar features as the horizontal linear blade slide assembly550, with the major difference being that the slide blade assembly guiderails 586/588 are replaced with slide blade assembly guide rails 602/604which are configured to slide the diagonal linear blade slide assembly600 in a diagonal direction as denoted by an arrow 606 indicating thesliding direction. The end bar 608 is similarly configured to receivethe diagonal linear blade slide assembly 600. In one embodiment, similarbonnet latch and catch pairs (not shown), discussed above, are includedto prevent rebounding of the diagonal linear blade slide assembly 600.

In another alternative embodiment, a vertical linear blade slideassembly 650 is depicted in FIG. 32. The vertical linear blade slideassembly 650 includes similar features as the horizontal linear bladeslide assembly 550, with the major difference being that the slide bladeassembly guide rails 586/588 are replaced with slide blade assemblyguide rails 652/654 which are configured to slide the vertical linearblade slide assembly 650 in a vertical direction as denoted by an arrow656 indicating the sliding direction. The end bar 658 is similarlyconfigured to receive the vertical linear blade slide assembly 650. Inone embodiment, similar bonnet latch and catch pairs (not shown),discussed above, are included to prevent rebounding of the verticallinear blade slide assembly 600.

Access to various safety system components may be provided by a tabletop hood assembly 700 of FIG. 33. The table top hood assembly 700 canalso be used to gain unimpeded access to a variety of equipment, e.g.,to replace the blade 108, under the work-piece support surface 104. Thetable top hood assembly 700 includes a hood 702, which is connected tothe housing 102 by hinges 704. A reinforcement member 706 providesadditional strength at the upper portion of the housing 102 to supportthe hood assembly 700. An opening 708 is configured to permit the blade108 to turn and be adjusted for height and bevel without interferencewith the hood 702.

Alignment members 710, shown in FIG. 34, are positioned on the innersurface of the hood 702. The alignment members, which are generallywedge shaped, cooperate with alignment members 712 on the housing 102(shown in FIG. 35) to align the hood 702 with the housing 102.Lock-downs 714 shown in FIG. 36 are pivotably connected to the undersideof the hood 702 for use with locking members 716 shown in FIG. 37 insecuring the hood 702 in a locked position aligned on top of the housing102.

The hinges 704 may be spring loaded hinges to assist in raising the hood702 and a lock bar (not shown) may be used to maintain the hood 702 inan open position. In alternative embodiments, the carriage assembly 120is directly mounted to the hood 702. In such embodiments, the springloaded hinges 704 may be aumented with one or more pneumatic cylinders.In one embodiment, two pneumatic cylinders may be provided to preventundue stress being applied to the hinges 704. Two or more pneumaticcylinders are particularly useful in embodiments wherein the carriageassembly is attached to the hood 702.

If desired, electrical cut-off switches (not shown) may be positioned onthe housing 102 so as to mate with electrical cut-off contacts (notshown) mounted on the hood 702 to ensure the table saw 100 is notenergized when the hood 702 is raised.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same should be considered asillustrative and not restrictive in character. It is understood thatonly the preferred embodiments have been presented and that all changes,modifications and further applications that come within the spirit ofthe invention are desired to be protected.

The invention claimed is:
 1. A table saw comprising: a work piecesupport surface; a swing arm assembly including a shaping device supportshaft, the swing arm assembly automatically retractable along aretraction path from a proximate position whereat the support shaft isproximate to the work piece support surface to a distal position whereatthe support shaft is distal to the work piece support surface; a stopbelt positioned across the retraction path; and a control systemconfigured to cause the swing arm assembly to retract along theretraction path in response to a sensed condition.
 2. The table saw ofclaim 1, wherein the stop belt comprises a stretchable material.
 3. Thetable saw of claim 2, wherein the stretchable material comprises a NYLONmaterial.
 4. The table saw of claim 1, wherein the retraction path issubstantially linear.
 5. The table saw of claim 1, wherein theretraction path is curved.
 6. The table saw of claim 5, furthercomprising: a latch hold mechanism; a swing arm movable along theretraction path, the shaping device support shaft rotatably supported bythe swing arm; a latch pin movable between a first latch pin positionwhereat the swing arm is maintained at a first swing arm position and asecond latch pin position whereat the swing arm is not maintained at thefirst swing arm position; and an actuating device configured to transfera first force to the latch pin to bias the latch pin in a directiontoward the second latch pin position, and, after transferring the firstforce, further configured to transfer a second force to the swing arm.7. The table saw of claim 6, further comprising: a frame supporting theswing arm, wherein the stop belt comprises a first anchor portionfixedly attached to the latch hold mechanism and a second anchor portionfixedly attached to the frame.
 8. The table saw of claim 7, wherein thefirst anchor portion is positioned closer to the work piece supportsurface than the second anchor portion.
 9. The table saw of claim 6,further comprising: a carriage supported by the frame and supporting theswing arm, the carriage positionable at a plurality of heights withrespect to the frame, wherein the retraction path is one of a pluralityof retraction paths, each of the plurality of retraction pathsassociated with a respective one of the plurality of heights, and thestop belt is positioned to intersect each of the plurality of retractionpaths.
 10. A table saw comprising: a work piece support surface; a swingarm movable along a swing arm path from a first swing arm positionwhereat an arbor shaft rotatably supported by the swing arm ispositioned proximate to the work piece support surface and a secondswing arm position whereat the arbor shaft is distal to the work piecesupport surface; a stop belt positioned across the swing arm path; and acontrol system configured to cause the swing arm to move along the swingarm path in response to a sensed condition.
 11. The table saw of claim10, wherein the stop belt comprises a stretchable material.
 12. Thetable saw of claim 11, wherein the stretchable material comprises aNYLON material.
 13. The table saw of claim 10, further comprising: alatch hold mechanism; a latch pin movable between a first latch pinposition whereat the swing arm is maintained at the first swing armposition and a second latch pin position whereat the swing arm is notmaintained at the first swing arm position; and an actuating deviceconfigured to generate a first force to bias the latch pin in adirection toward the second latch position, and, after transferring thefirst force, further configured to transfer a second force to the swingarm.
 14. The table saw of claim 13, further comprising: a framesupporting the swing arm, wherein the stop belt comprises a first anchorportion fixedly attached to the latch hold mechanism and a second anchorportion fixedly attached to the frame.
 15. The table saw of claim 14,wherein the first anchor portion is positioned closer to the work piecesupport surface than the second anchor portion.